1 Topic by StanleyElephant

  • StanleyElephant
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  • Registered: 2018-02-15
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Topic: Laser Voltage spec

Hi all,
forgive me if this is a stupid question, I tried searching the forum and couldn't come up with anything.

The "old" pcb that's posted on freelss.org has two trimmer resistors for fine-tuning the voltage on the lasers.
5V input - ~1.3V drop across the ULN2003 = 3.7V, then the remaining voltage drop is done through the trimmer to get 3.3V for the lasers.

The "new" pcb (elsewhere on this forum) skips the trimmer resistors entirely, feeding the lasers with the 3.7V

My question, is this extra voltage going to have any adverse effect on the life or performance of the lasers?

2 Reply by carl_m1968

  • carl_m1968
  • carl_m1968
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  • Registered: 2014-10-17
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Re: Laser Voltage spec

StanleyElephant wrote:

Hi all,
forgive me if this is a stupid question, I tried searching the forum and couldn't come up with anything.

The "old" pcb that's posted on freelss.org has two trimmer resistors for fine-tuning the voltage on the lasers.
5V input - ~1.3V drop across the ULN2003 = 3.7V, then the remaining voltage drop is done through the trimmer to get 3.3V for the lasers.

The "new" pcb (elsewhere on this forum) skips the trimmer resistors entirely, feeding the lasers with the 3.7V

My question, is this extra voltage going to have any adverse effect on the life or performance of the lasers?


You are talking about .4 volts. so no. Lasers are more sensitive to current fluctuations than voltage. Most laser power supplies monitor control current tighter than voltage.

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